Spent 4 days touring/learning/taking observations around the Morrell Mountain area in the Southern Swans. I realize this is out of the forecast area, but it's the same range with a similar snowpack structure to what we've been seeing in our neck of the woods this year. Our group got to see how well the holiday crusts and NYE storm are playing together, which is, not very nicely. There was no freezing rain crust here but rather the Christmas Eve melt/freeze crust overloaded by the NYE snow. We saw numerous natural avalanches which were large relative to their path mostly on east and south east aspects at/above treeline.
A couple notes on our stability tests include:
CTH with sudden collapse 65cm from snow surface in a east facing pit at 7050', no propagation in extended column tests at same location, conducted a PST in the same location twice with the results of PST 30/100 (End) down 65cm 181223, that's a best guess on the date, the other result was PST 40/100 (End) down 65cm on same layer. We expected propation in the ECT but didn't get any play on the layer. This was dug on 1/3.
CTM with sudden collapse 115 cm from surface on basal facets. HS 130cm. We were less concerned about this layer due to it's depth in the snowpack and noting that none of the avalanches we saw stepped down, not to say it couldn't be a player in shallower areas of the snowpack.
We skied east and south east facing aspects keeping it under 30 degrees mostly, and a west aspect up to 32 degrees. One group member noted a large collapse but other than that there was no cracking or whumphing observed.
Two photos are attached of one of the avalanche, sorry for the blurriness on the sides. The photo with the arrows shows the extent of the crown, it continues out of frame to the southern flank of the bowl... Pretty impressive to see the extent. We surmised it failed on the same persistent layer 65cm from surface on a crust/surface hoar combo. It will be exciting to see what the next storm does to this mixed bag of crust/facet combos.
Location approximate. From obs on Missoula Regional Avalanche Center website:
2 significant d3 persistent slabs on SE aspects. Crowns were r4-5. Full paths. Probably ran during new years storm event. These slabs ran on a layer of surface hoar/facets above the 12/21 melt freeze crust 65cm down.
